On Tue, Jun 11, 2019 at 09:47:02PM +0200, Borislav Petkov wrote: > On Tue, Jun 11, 2019 at 11:19:20AM -0700, Fenghua Yu wrote: > > So can I re-organize word 11 and 12 as follows? > > > > 1. Change word 11 to host scattered features. > > 2. Move the previos features in word 11 and word 12 to word 11: > > /* > > * Extended auxiliary flags: Linux defined - For features scattered in > > various > > * CPUID levels and sub-leaves like CPUID level 7 and sub-leaf 1, etc, word > > 19. > > */ > > #define X86_FEATURE_CQM_LLC (11*32+ 0) /* LLC QoS if 1 */ > > #define X86_FEATURE_CQM_OCCUP_LLC (11*32+ 1) /* LLC occupancy > > monitoring */ > > #define X86_FEATURE_CQM_MBM_TOTAL (11*32+ 2) /* LLC Total MBM > > monitoring */ > > #define X86_FEATURE_CQM_MBM_LOCAL (11*32+ 3) /* LLC Local MBM > > monitoring */ > > Yap. > > > 3. Change word 12 to host CPUID.(EAX=7,ECX=1):EAX: > > /* Intel-defined CPU features, CPUID level 0x7:1 (EAX), word 12 */ > > #define X86_FEATURE_AVX512_BF16 (12*32+ 0) /* BFLOAT16 instructions > > */ > > This needs to be (12*32+ 5) if word 12 is going to map leaf > CPUID.(EAX=7,ECX=1):EAX. > > At least judging from the arch extensions doc which lists EAX as: > > Bits 04-00: Reserved. > Bit 05: AVX512_BF16. Vector Neural Network Instructions supporting BFLOAT16 > inputs and conversion instructions from IEEE single precision. > Bits 31-06: Reserved. > > > 4. Do other necessary changes to match the new word 11 and word 12. > > But split in two patches: first does steps 1+2, second patch adds the > new leaf to word 12.
Currently KVM doesn't simulate scattered features (the ones in CPUID_LNX_* in cpuid_leafs) as reverse_cpuid[] doesn't contain CPUID_LNX_*. After the X86_FEATURES_CQM_* features are changed to scattered features, they will not be simulated by KVM any more as CPUID_F_0_EDX and CPUID_F_1_EDX are removed. Should patch #1 simulate X86_FEATURE_CQM_* in KVM? Or let KVM guys handle the scattered features? Thanks. -Fenghua
